Use of UAS and TLS technology in 3D modeling of constructions with complex architecture

Abstract

3D building models are widely used in many applications. The use of terrestrial laser scanning and UAS photogrammetry for 3D modelling is a popular practice especially for constructions with complex architecture. The present article presents an example of using these technologies successfully for 3D modelling of the Episcopal Cathedral of the Holy Trinity from Baia Mare, Romania. A number of 51 control and verification points were determined by the closed circuit travel method and the intersection method. All measurements were processed in Terramodel software. The control points used in the georeferencing of the scans were materialized by metal stakes and the verification points were materialized by reflective targets. Depending on the construction configuration, the field of view and the minimum/maximum scanning distances were subsequently set. A total of 45 scans were performed to model the entire cathedral. The photogrammetric flight was performed in RTK mode, with corrections being transmitted from the DJI D-RTK-2 Mobile Station base to the RTK drone. All retrieved frames had geolocation and frame orientation elements recorded by the IMU module. A total number of 222 photograms were taken, as a result of a double grid photogrammetric flight, with the camera oriented at 60 degrees, but also as a result of manual acquisition by performing orbital flights at different heights: an orbital flight on the ground floor, an orbital flight at the level of about 40 meters and an orbital flight around the tower.

Non-Destructive Measurements for 3D Modeling and Monitoring of Large Buildings Using Terrestrial Laser Scanning and Unmanned Aerial Systems

“…The modeling/monitoring geodetic network was materialized on the ground, as seen in Figure 3 (yellow-the traverse; orange-resections; green-side shots). The most well-known methods of data acquisition are registration, carried out via the free-stationing technique with the help of the three-dimensional intersection of the sights to the scanned targets; the determination of each station point via resection; registration executed by stationing at points of known coordinates; or registration using constraint points in order to perform the registration of the point clouds [10].…”

“…Their primary uses are in the fields of observation, monitoring, mapping, 3D modeling, and 3D reconstruction, but they also find applications in archeology, remote sensing, environmental science, geophysics, and related fields [ 9 ]. Digital maps, complex point clouds, georeferenced orthophotomaps, digital elevation models (DEMs), and digital surface models (DSMs) can all be obtained with the help of such implementations and can be used for spatial analysis and in GIS programs [ 10 , 11 , 12 ].…”

“…Unmanned Aerial Systems (UASs) [ 9 ], terrestrial laser scanning (TLS) [ 10 ], laser interferometry [ 29 ], and microwave interferometry (MI) [ 30 ] are examples of applicable technologies for contactless measurements. However, by comparing all these technologies with each other and also comparing them with other classic contactless measuring technologies, TLS and UASs turn out to be the technologies that provide the best spatially distributed acquisition of structural responses.…”